cloth with wind and physics?

How can i get wind blown cloth with physics (objects colliding realistically) in unity 5?
I know how to make a vertex animation shader for wind blown cloth, but its not very realistic and would look crap when combined with physics.

 

This sounds like a good topic. I've yet to see much talk about cloth using U5.

 

Unity got rid of interactive cloth, which is probably what you are looking for. The cloth you see now in Unity5 is specifically designed for clothes on characters or something similar.
Maybe there is an Asset that has what you are looking for.

 

The new cloth works brilliantly and isn't limited to characters. It can be pushed around by any sphere or capsule collider, but it cannot exert a force back on anything.

 

Where would you start? Is there a tutorial anywhere?

For instance, how about a square cloth covering a wooden crate or something like that. Or the cloth falling on the box?

 

Unfortunately you can't really make a box very well out of capsules and spheres, so that particular example wont work very well.

All you do is add the cloth component to your object. Then if you want you can fix some of the vertices to their original position and/or add some colliders. There's some options for wind like forces as well.

 

For the physic with other items (with other colliders than spheres and capsules), I can't really help.

But a way of applying wind is to add to the Random Acceleration and External Acceleration of the cloth which will allow the cloth to move toward its local direction. Note that the random acceleration is really crappy for anything less than strong winds as it generate a new force way too often. As for the External Acceleration, it's mostly for things like constant winds/stream of force. If you want a gentle breeze or some indirect wind, you will mostly have to add a custom script that will allow the acceleration to be adjusted at the right speed.

For example, I created this CSharp script this :

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class ClothOnWind : MonoBehaviour {
5.  
6.     private Cloth clothMod;
7.     private Vector3 TargetWindForce;
8.  
9.     public Vector3 MaxWindForce;
10.     public float WindForceIntervals = 1;
11.     public Vector3 NegativeWindForce;
12.  
13.     // Use this for initialization
14.     void Start () {
15.         clothMod = this.GetComponent<Cloth> ();
16.         clothMod.externalAcceleration = NegativeWindForce;
17.         TargetWindForce = MaxWindForce;
18.         if (WindForceIntervals <= 0) {
19.             WindForceIntervals = 0.1f;
20.         }
21.     }
22.  
23.     // Update is called once per frame
24.     void Update () {
25.         clothMod.externalAcceleration = Vector3.MoveTowards (clothMod.externalAcceleration, TargetWindForce, WindForceIntervals * Time.deltaTime);
26.  
27.         if (clothMod.externalAcceleration == MaxWindForce) {
28.             TargetWindForce = NegativeWindForce;
29.         }
30.         if (clothMod.externalAcceleration == NegativeWindForce) {
31.             TargetWindForce = MaxWindForce;
32.         }
33.     }
34. }
35.  

You just have to place this script on the GameObject with the cloth component.
This script will make the external acceleration of your choice being alternated between its full power and its negative power so that it looks like the wind blows are inconsistent.
If you wish, you could simplify it by making a direct uses of the cloth's settings for the external acceleration's maximum value (in the inspector), but I was damn lazy and decided to make it as an additional thing.

If you really wish to make use of your wind component, you could make a script like this to look up for its position and orientation as well as wind force and add it onto to the external force. (Can't help you much on this one. Could do it, but my head is already all over my own project)

If anyone is using this script, I highly suggest to add a tiny bit of random acceleration in the same direction as for the main external force just for the sake of making it less repetitive.

= EDIT =
I would like to add that with Unity 5 Cloth's Editable Constraints, you can also control easily how much each part of the cloth will bend with this script. For example, by making the "attached" part of the constraint (in the Cloth's Edit Constraint) at 0 and smoothly removing the constraint (from 0 to 1) towards the end of the cloths, this will allow a smooth and slight gliding effect on the cloth.

 

You mean something like this:

The cloth looks like this:


The wind force is applied like this:

Code (CSharp):

1. //Sail Controller class
2. void SetWindForces()
3.         {
4.             if (windPower == null || windPower != windController.GetWindPower() || windDirection == null || windDirection != windController.GetWindDirection())
5.             {
6.                 Debug.Log("Set Wind in Sails");
7.                 windPower = windController.GetWindPower();
8.                 windDirection = windController.GetWindDirection();
9.  
10.                 float x = 0;
11.                 float z = 0;
12.  
13.                 if (windDirection <= 90)
14.                 {
15.                     x = Mathf.Sin(windDirection*Mathf.Deg2Rad) * windPower;
16.                     z = Mathf.Cos(windDirection*Mathf.Deg2Rad) * windPower;
17.                 }
18.                 else if (windDirection > 90 && windDirection <= 180)
19.                 {
20.                     z = Mathf.Sin((windDirection-90)*Mathf.Deg2Rad) * windPower * -1;
21.                     x = Mathf.Cos((windDirection-90)*Mathf.Deg2Rad) * windPower;
22.                 }
23.                 else if (windDirection > 180 && windDirection <= 270)
24.                 {
25.                     x = Mathf.Sin((windDirection-180)*Mathf.Deg2Rad) * windPower * -1;
26.                     z = Mathf.Cos((windDirection-180)*Mathf.Deg2Rad) * windPower * -1;
27.                 }
28.                 else
29.                 {
30.                     z = Mathf.Sin((windDirection-270)*Mathf.Deg2Rad) * windPower;
31.                     x = Mathf.Cos((windDirection-270)*Mathf.Deg2Rad) * windPower * -1;
32.                 }
33.  
34.  
35.                 windForces = new Vector3(x, 0f, z);
36.  
37.                 foreach (WoP_Sail sail in sails)
38.                 {
39.                     sail.SetWindForces(windForces);
40.                 }
41.  
42.             }
43.         }
44.  
45. //------------------------------------------------------------
46. //Sail Class
47.  
48.  
49. public void SetWindForces(Vector3 wind)
50.         {
51.             windForces = wind;
52.             if (sailCloth != null)
53.             {
54.                 sailCloth.externalAcceleration = windForces;
55.             }
56.         }
57.  
58.  

With that solution I now have the following problem:
If the sail mesh is double sided it works fine, if it is a one sided mesh the wind force is 180°. So the sail fills in the opposite direction.
And it doesnt matter how the axis of the mesh are oriented

 

sniperisa,
Thanks for putting up those snippets; I appreciate your sharing.
I am making a simplistic sailing simulator and your code helped me immensely.
-- Paul

 

I have created a package called "Forces and Simulations" It can affect Rigidbodies, Particle Systems and Cloths you can find it on Unity Asset Store https://www.assetstore.unity3d.com/en/#!/content/16109

 

The link is not working and it takes me to main page.